Chemistry for chemical vapor deposition of titanium containing films

ABSTRACT

Titanium-containing films exhibiting excellent uniformity and step coverage are deposited on semiconductor wafers in a cold wall reactor which has been modified to discharge plasma into the reaction chamber. Titanium tetrabromide, titanium tetraiodide, or titanium tetrachloride, along with hydrogen, enter the reaction chamber and come in contact with a heated semiconductor wafer, thereby depositing a thin titanium-containing film on the wafer&#39;s surface. Step coverage and deposition rate are enhanced by the presence of the plasma. The use of titanium tetrabromide or titanium tetraiodide instead of titanium tetrachloride also increases the deposition rate and allows for a lower reaction temperature. Titanium silicide and titanium nitride can also be deposited by this method by varying the gas incorporated with the titanium precursors.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to the field ofintegrated circuit manufacturing technology and, more particularly, toan improved method for depositing thin films.

[0003] 2. Background of the Related Art

[0004] In the manufacturing of integrated circuits, numerousmicroelectronic circuits are simultaneously manufactured onsemiconductor substrates. These substrates are usually referred to aswafers. A typical wafer is comprised of a number of different regions,known as die regions. When fabrication is complete, the wafer is cutalong these die regions to form individual die. Each die contains atleast one microelectronic circuit, which is typically replicated on eachdie. One example of a microelectronic circuit which can be fabricated inthis way is a dynamic random access memory (“DRAM”).

[0005] Although referred to as semiconductor devices, integratedcircuits are in fact fabricated from numerous materials of varyingelectrical properties. These materials include insulators ordielectrics, such as silicon dioxide, and conductors, such as aluminumor tungsten, in addition to semiconductors, such as silicon andgermanium.

[0006] In the manufacture of integrated circuits, conductive paths areformed to connect different circuit elements that have been fabricatedwithin a die. One method to make these connections is through the use ofopenings in intermediate insulative layers. These openings are typicallyreferred to as “contact openings” or “vias.” A contact opening istypically created to expose an active region, commonly referred to as adoped region, while vias traditionally refer to any conductive pathbetween any two or more layers in a semiconductor device.

[0007] After a contact opening, for instance, has been formed to exposean active region of the semiconductor substrate, an enhanced doping maybe performed through the opening to create a localized region ofincreased carrier density within the bulk substrate. This enhancedregion provides a better electrical connection with the conductivematerial which is subsequently deposited within the opening. One methodof increasing conductivity further involves the deposition of a thintitanium-containing film, such as titanium silicide, over the wafer sothat it covers the enhanced region prior to deposition of the conductivelayer. Thin films of titanium-containing compounds also find other usesas well in the fabrication of integrated circuits. For example, titaniumnitride is used as a diffusion barrier to prevent chemical attack of thesubstrate, as well as to provide a good adhesive surface for thesubsequent deposition of tungsten.

[0008] Indeed, many reasons exist for depositing thin films betweenadjacent layers in a semiconductor device. For example, thin films maybe used to prevent interdiffusion between adjacent layers or to increaseadhesion between adjacent layers. Titanium nitride, titanium silicide,and metallic titanium are known in the art as materials that can bedeposited as thin films to facilitate adhesion and to reduceinterdiffusion between the layers of a semiconductor device. Other filmsthat may be useful for these purposes also include titanium tungsten,tantalum nitride, and the ternary alloy composed of titanium, aluminum,and nitrogen.

[0009] The deposition of titanium-containing films is just one exampleof a step in the manufacture of semiconductor wafers. Indeed, any numberof thin films, insulators, semiconductors, and conductors may bedeposited onto a wafer to fabricate an integrated circuit. As the sizeof the microelectronic circuits, and therefore the size of die regions,decreases, the percentage of reliable circuits produced on any one waferbecomes highly dependent on the ability to deposit these thin filmsuniformly across the surface of the wafer. This includes uniformdeposition on horizontal surfaces, slanted surfaces, and verticalsurfaces, including those surfaces which define the walls and base ofcontacts and vias. If these thin films are not deposited in a uniformmanner, gaps may be created which prevent the thin film from fullyperforming its function. The likelihood of the existence of these gapstends to increase as the films become thinner.

[0010] Films may be deposited by several different methods, such asthermal growth, sputter deposition, spin-on deposition, chemical vapordeposition (CVD), and plasma enhanced chemical vapor deposition (PECVD).In thermal growth, the wafer substrate is heated at precisely controlledtemperatures, typically between 800 and 1200° C., with a choice ofambient gases. The high temperature promotes the reaction between theambient gas and the wafer substrate. For instance, films of silicondioxide are often produced by this method. The problem with this methodis the extremely high deposition temperatures required. Extremely hightemperatures are a concern for two reasons. First, high temperature maybe incompatible with or even detrimental to other elements of theintegrated circuit, and, second, excessive cycling from low to hightemperatures can damage a circuit, thereby reducing the percentage ofreliable circuits produced from a wafer. Therefore, a lower depositiontemperature is typically preferred as long as the characteristics of thedeposited film are unaffected.

[0011] In sputter deposition, the material to be deposited is bombardedwith positive inert ions. Once the material exceeds its heat ofsublimation, atoms are ejected into the gas phase where they aresubsequently deposited onto the substrate, which may or may not benegatively biased. Sputter deposition has been widely used in integratedcircuit processes to deposit titanium-containing films. The primarydisadvantage of sputter deposition is that it results in films havingpoor step coverage, so it may not be widely useable in submicronprocesses. Films deposited by sputter deposition on slanted or verticalsurfaces do not exhibit uniform thickness, and the density of filmsdeposited on these surfaces is usually not as high as the filmsdeposited on horizontal surfaces.

[0012] In spin-on deposition, the material to be deposited is mixed witha suitable solvent and spun onto the substrate. The primary disadvantageof spin-on deposition is that nominal uniformity can only be achieved atrelatively high thicknesses. Therefore, this method is primarily usedfor the deposition of photoresist and the like. It is generally notuseful for the deposition of thin films.

[0013] As previously indicated, the trend for reducing the size of dieregions has dictated the reduction of the thickness of many depositedfilms. These thin films need to have improved step coverage to reducethe number of gaps in the films and to increase the yield of operabledevices. Of the methods discussed above, CVD and PECVD are best suitedto deposit the thinnest films, as films deposited by sputter depositionon slanted or vertical surfaces do not exhibit the degree of uniformityobtainable by CVD and PECVD.

[0014] In CVD, the gas phase reduction of highly reactive chemicalsunder low pressure results in very uniform thin films. A basic CVDprocess used for depositing titanium involves a given composition ofreactant gases and a diluent which are injected into a reactorcontaining one or more silicon wafers. The reactor is maintained atselected pressures and temperatures sufficient to initiate a reactionbetween the reactant gases. The reaction results in the deposition of athin film on the wafer. If the gases include hydrogen and a titaniumprecursor, a titanium-containing film will be deposited. For example,if, in addition to hydrogen and the titanium precursor, the reactorcontains a sufficient quantity of nitrogen or a silane, the resultingtitanium-containing film will be titanium nitride and titanium suiciderespectively. Plasma enhanced CVD is a form of CVD that includesbombarding the material to be deposited with a plasma to generatechemically reactive species at relatively low temperatures.

[0015] Chemical vapor deposition is typically carried out in one of twotypes of reactor. One type of reactor is called a hot wall reactor. Ahot wall reactor is operated at a low pressure, typically 1 Torr orless, and high temperatures, typically 600° C. or greater. The othertype of reactor is called a cold wall reactor. A cold wall reactor isoperated at atmospheric pressure and low temperatures, typically 400 to600° C.

[0016] The primary advantage of the hot wall reactor is that depositedfilms exhibit excellent purity and uniform step coverage. However, thehot wall reactor process is also characterized by low deposition rates,high temperatures, and the potential for the occurrence of unwantedreactions on the walls of the reaction chamber. Conversely, the coldwall reactor exhibits high deposition rates but poor step coverage.

[0017] Exposure to extreme temperatures and excessive cycling from lowto high temperatures during the fabrication of integrated circuits canrender the circuits useless. Therefore, a process for depositing filmsexhibiting uniform step coverage that can be conducted with a minimum ofexposure to elevated temperatures could have a dramatic impact on theyield of reliable circuits. It has been thought that PECVD is the bestmethod of achieving this result. In fact, plasma deposition has beenused to produce titanium-containing films in a cold wall reactormaintained at approximately 400° C. The result of this deposition isthin titanium-containing films exhibiting good step coverage and growthrate.

[0018] However, the current plasma deposition technology does have itslimitations. Because of the higher pressures associated with depositionin a cold wall reactor, it is difficult to deposit films that exhibit ahigh degree of uniform coverage in contacts and vias having high aspectratios. This difficulty extends to both the vertical surfaces of thecontacts and vias as well as the horizontal surfaces at the base of thecontacts and vias.

[0019] The present invention may address one or more of the problems setforth above.

SUMMARY OF THE INVENTION

[0020] Certain aspects commensurate in scope with the originally claimedinvention are set forth below. It should be understood that theseaspects are presented merely to provide the reader with a brief summaryof certain forms the invention might take and that these aspects are notintended to limit the scope of the invention. Indeed, the invention mayencompass a variety of aspects that may not be set forth below.

[0021] In accordance with one aspect of the present invention, there isprovided a chemical vapor deposition process for depositing a titaniumcontaining film on a substrate. The process includes the steps of: a)disposing the substrate inside a reaction chamber; b) bringing thesubstrate to a given temperature; c) introducing a titanium source gas,the titanium source gas being at least one of titanium bromide andtitanium iodide, into the reaction chamber; d) introducing a reactantgas of at least one of hydrogen, silane, nitrogen and mixtures thereofinto the reaction chamber; and e) discharging plasma inside the reactionchamber to deposit the titanium containing film onto the substrate.

[0022] In accordance another aspect of the present invention, there isprovided a chemical vapor deposition process for depositing film on asubstrate. The process includes the steps of: a) disposing the substrateinside a cold wall reaction chamber; b) bringing the substrate to agiven temperature; c) introducing a titanium source gas selected fromthe group consisting of titanium bromide and titanium iodide into thereaction chamber; d) introducing a reactant gas of at least one ofhydrogen, silane, nitrogen and mixtures thereof into the reactionchamber; and e) discharging plasma inside the reaction chamber todeposit the titanium containing film onto the substrate.

[0023] In accordance with still another aspect of the present invention,there is provided a chemical vapor deposition process for depositingtitanium-containing films on a substrate. The process includes the stepsof: a) disposing the substrate inside a reaction chamber maintained at agiven temperature; b) introducing a titanium source gas into thereaction chamber; c) introducing a reactant gas into the reactionchamber; d) discharging plasma inside the reaction chamber and applyinga voltage to substrate to bias the substrate to deposit atitanium-containing film onto the substrate.

[0024] In accordance with yet another aspect of the present invention,there is provided a chemical vapor deposition process for depositing atitanium-containing film on a substrate. The process includes the stepsof: a) disposing the substrate inside a cold wall reaction chambermaintained at a given temperature; b) introducing a titanium source gasinto the reaction chamber; c) introducing a reactant gas of at least oneof hydrogen, silane, nitrogen, and mixtures thereof into the reactionchamber; and d) discharging plasma inside the reaction chamber andapplying a voltage to the surface of the wafer to bias the surface todeposit the titanium-containing film onto the substrate.

[0025] In accordance with a further aspect of the present invention,there is provided an in-situ plasma cleaning process for cleaningcontact openings. The process includes the steps of: a) disposing asubstrate having contact openings inside a reaction chamber; b) bringingthe substrate to a given temperature; c) introducing a cleaning agent ofat least one of hydrogen, argon, or nitrogen trifluoride into thereaction chamber; d) discharging plasma inside the reaction chamber andapplying a voltage to the substrate to bias the substrate to removematerial from within the contact openings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The foregoing and other advantages of the invention will becomeapparent upon reading the following detailed description and uponreference to the drawings in which:

[0027]FIG. 1 illustrate a semiconductor wafer and its constituent dieregions;

[0028]FIG. 2 is a diagrammatic cross-section of a semiconductor waferprocessed in accordance with the present invention, wherein a thin filmhas been deposited onto the surface of a die including the surfaces of acontact opening;

[0029]FIG. 3 is a diagrammatic cross-section of a semiconductor waferprocessed in accordance with the present invention, wherein a conductivelayer has been deposited onto the thin film previously deposited; and

[0030]FIG. 4 is schematic diagram of a cold wall reactor used inchemical vapor deposition processes which has been modified to dischargeplasma into the reaction chamber and which has been further modified toapply a voltage to the surface of the die.

DESCRIPTION OF SPECIFIC EMBODIMENTS

[0031] In the interest of clarity, not all features of an actualimplementation into an integrated circuit process are described in thisspecification. This illustration is restricted to those aspects of anintegrated circuit process involving the deposition of thin films.Conventional details of integrated circuit processes, such as maskgeneration, resist casting, resist development, etching, doping,cleaning, implantation and annealing are not presented as such detailsare well known in the art of integrated circuit manufacture.

[0032] Turning now to the drawings, a typical semiconductor wafer isillustrated in FIG. 1 and designated by a reference numeral 10. Thewafer 10 includes a number of different regions, known as die regions12. Each die region 12 may include an integrated circuit containingvarious features and fabricated using various materials and processes.For the purposes of this discussion, one of the die regions 12 will bediscussed. The die region 12 includes a thin titanium-containing film.An example of such a film is illustrated in FIG. 2. Specifically, FIG. 2illustrates a cross-sectional view of a die region 12 which includes anenhanced doped region or active region 24 within a semiconductorsubstrate 26. The active region 24 by be formed by an implantationprocess, for instance. The bulk substrate 26 is coated with aninsulative layer 22, such as borophosphosilicate glass (BPSG) orphosphosilicate glass (PSG). The insulative layer 22 is etched to form acontact opening 20 through the insulative layer 22 to the active region24. Of course it should be understood that the depiction of a contactopening to an active region is merely exemplary of a high-aspect ratiofeature and that this discussion applies to other high-aspect ratiofeatures, such as vias, as well.

[0033] Using the method described in detail below, a layer of titaniumor titanium-containing film 28 is deposited across the wafer such thatit lines the contact opening 20. The film 28 exhibits good adhesion tothe contact opening 20 and the active region 24, along with excellentstep coverage. The film 28 also exhibits good adhesion to a subsequentlydeposited conductive metal layer 21 illustrated in FIG. 3.

[0034] By known CVD processes, the only way good step coverage could beachieved was by deposition in a hot wall reactor. However, deposition inthe hot wall reactor was achieved at low deposition rates and was oftenaccompanied by unwanted reactions which occurred at the walls of thereactor. Conversely, use of a traditional cold wall reactor achievedmore favorable deposition rates but sacrificed good step coverage. Whena cold wall reactor is modified to discharge plasma into the reactionchamber, thin films are deposited that exhibit good step coverage as aresult of using titanium tetrachloride as the titanium gas source.

[0035] To perform the deposition of the film 28, a cold wall CVD reactor30 is advantageously used, as illustrated in FIG. 3, although asimilarly modified hot wall reactor may also be used under theconditions set forth below to achieve improvements. The cold wall CVDreactor 30 is modified with an RF generator 32. A titanium source gas,advantageously obtained from a titanium halide such as titaniumtetrachloride, titanium bromide, or titanium iodide, and hydrogen areintroduced into the reaction chamber 34 through a shower head 31. If sodesired, a carrier gas, such as argon or helium, may be added to thereactant gases. The gases may or may not be pre-mixed. The gases aregenerally introduced through the shower head 31 to achieve gooddispersion of the gases, but the gases can be introduced by other means.Desired reaction pressures are maintained by conventional pressurecontrol components, including a pressure sensor 33, a pressure switch35, an air operating vacuum valve 37, and a pressure control valve 39.The carrier gas and the resultant gas, such as HCl when titaniumtetrachloride is used as the titanium precursor, given off during thereaction escapes from the reaction chamber 34 through an exhaust vent42. These gases pass through a particulate filter 44, and gas removal isfacilitated by a roots blower 46.

[0036] In the reactor chamber 34, a substrate holder 36 is heated to atemperature of less than 600° C., and typically less than 400° C. Infact, temperatures may be in the range of 200 to 350° C., with pressuresin the range of 0.2 to 2.0 Torr. Heating may be achieved through the useof halogen lamps 38, so that the silicon wafer 10 is heated byconvection. As the reactant gases enter the reaction chamber 34 throughthe shower head 31, a voltage is applied between the substrate holder 36and the reaction chamber 34 for a period of from about 50 to 150 secondstypically. The voltage may be supplied by an RF generator 32 with oneline 48 a coupled to a wall of the reaction chamber 34 and another line48 b coupled to the substrate holder 36. The RF voltage causes theionization of hydrogen gas present as a reactant to create a plasma ofH⁺ ions. The plasma is discharged in the space above the wafer 10 tofacilitate the deposition reaction.

[0037] If no further modification to the deposition process is made,films 28 are deposited at relatively high rates. These films 28 exhibitgood step coverage which is not inherent in a cold wall reactor systemin which plasma is not used. However, deposition along the surfaces ofcontacts 20 and vias is generally not optimal because the pressuresassociated with deposition preclude optimal deposition in the recessesof these conductive paths, particularly when a cold wall CVD reactor isemployed.

[0038] However, a voltage, such as an RF voltage, may be applied to thesurface of the wafer 10 via a line 48 c from the RF generator 32. Ifthis voltage is applied as the plasma is being discharged above thewafer 10, further improvements in step coverage can be achieved. Inparticular, step coverage along the surfaces of the contact 20 isimproved. The applied voltage causes the surface of the wafer 10 tobecome biased. The charged surface attracts oppositely charged speciesfrom the space above the wafer 10. The charged species are drawn to thesurface overcoming the pressures which had previously hindereddeposition. Typically the surface of the wafer 10 is negatively biasedto attract the positive metal cations.

[0039] As a cumulative result of this process, a chemical reactionoccurs which results in the deposition of a titanium-containing film 28along the exposed surfaces of the wafer 10. These surfaces include thevertical and horizontal surfaces of the contact 20. The deposited films28 exhibit uniform step coverage. In particular, the vertical andhorizontal surfaces of the contact 20 exhibit improved step coveragecompared to films 28 deposited onto the surface of a wafer 10 which hasnot been biased. The films 28 which are typically deposited by thisprocess using titanium tetrachloride are generally less than 3000 Åthick, and the reaction can be characterized as TiCl₄+2H₂→Ti+4HCl. Thedeposition of titanium from titanium tetrachloride in this mannergenerally requires an exposure period greater than 200 seconds.

[0040] Optionally, a reducing agent can be introduced into the reactionchamber 34 along with the titanium precursor and hydrogen. When thisreducing agent is nitrogen, the titanium-containing film 28 which isdeposited onto the wafer 10 is composed principally of titanium nitride,and the reaction can be characterized by 2TiCl₄+4H₂+N₂→2TiN+8HCl. Whenthe reducing agent is a silane, the titanium containing film 28 which isdeposited onto the wafer 10 is composed principally of elementaltitanium and titanium silicide, and the reaction can be characterized by3TiCl₄+2H₂+2SiH₄→2Ti+TiSi₂+12HCl.

[0041] As mentioned above, the modified reactor may contain titaniumtetrabromide or titanium tetraiodide as the titanium source gas, insteadof titanium tetrachloride. This results in the deposition of thintitanium films exhibiting good step coverage. It has been found thatthis deposition can be achieved at lower temperatures and in a shorterperiod of time as compared with known methods, partly as a result oftitanium tetrabromide and titanium tetraiodide being more reactive thantitanium tetrachloride. This results in a faster deposition rate of thetitanium film, and allows for the reaction to be conducted at lowertemperatures. For instance, the deposition of titanium-containing filmsexhibiting good step coverage can be achieved in less than 200 secondsof exposure at temperatures less than 350° C. The chemical reaction canbe characterized by TiBr₄(or TiI₄)+2H₂→Ti+4HBr(or 4HI).

[0042] The presence of the plasma allows for good step coverage underthe temperature conditions normally employed in a cold wall reactor.Also, the wafer 10 may be biased as discussed above so that the materialto be deposited is drawn into the contact 20 or via to improve the stepcoverage of the deposited film. Furthermore, as discussed previously, areducing agent can be introduced into the reactor chamber along with thetitanium precursor and hydrogen. When this reducing agent is nitrogen,the titanium-containing film deposited onto the wafer is composedprincipally of titanium nitride, and the reaction can be characterizedby 2TiBr₄(or 2TiI₄)+4H₂+N₂→2TiN+8HBr(or 8HI). When the reducing agent isa silane, the titanium containing film deposited onto the wafer iscomposed principally of elemental titanium and titanium silicide, andthe reaction can be characterized by 3TiBr₄(or3TiI₄)+2H₂+2SiH₄→2Ti+TiSi₂+12HBr(or 12HI).

[0043] As the size of devices decreases the thickness of these films 28,whether used as diffusion barriers or adhesive layers, also decreases.By ensuring the highest degree of uniform step coverage, the likelihoodof producing a higher percentage of reliable devices increases.Additionally, depositing films 28 as discussed above results in a higherdeposition rate. Because the deposited material is drawn into thecontacts 20 and vias, the films 28 are deposited in a shorter period oftime. This ability to deposit films 28 in a shorter period of time alsoincreases the likelihood of obtaining a higher yield of reliablecircuits. The barrier properties and adhesive properties of thedeposited films 28 are generally at their lowest at elevatedtemperatures. Therefore, the longer the period of exposure to elevatedtemperatures, the greater the likelihood of producing faulty devices.Because deposition by the described methods results in deposition in ashorter period of time, the amount of time the wafer 10 is exposed toelevated temperatures decreases.

[0044] Furthermore, the methods may serve other uses. For example, anin-situ plasma cleaning of the surfaces of the contact or via, inparticular the base of these conductive paths, can be conducted. It isnot uncommon for oxides, particularly oxides of silicon, to form duringsemiconductor processes. The presence of these oxides is generally notdesired. To conduct the cleaning operation which removes the unwantedoxides, the deposition process previously described is employed exceptthat hydrogen, argon, and nitrogen trifluoride are charged to thereactor. When plasma is then discharged in the reactor, the oxide ofsilicon is converted into a volatile product, such as SiF₄, which isreadily removed. If, in addition to discharging plasma into the reactor,a voltage is applied to the surface of the wafer to bias that surfacenegatively, the cleaning operation's efficiency at removing unwantedoxide deposits located along the walls and base of contacts and vias isincreased. Without this modification, the cleaning agents may notovercome the reaction pressures and penetrate the recesses of thecontacts and vias.

[0045] While the invention is susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and will be described in detail herein. However,it should be understood that the invention is not intended to be limitedto the particular forms disclosed. Rather, the invention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the invention as defined by the following appended claims.

What is claimed is:
 1. A chemical vapor deposition process fordepositing a titanium containing film on a substrate, the processcomprising the steps of: a) disposing the substrate inside a reactionchamber; b) bringing the substrate to a given temperature; c)introducing a titanium source gas, the titanium source gas being atleast one of titanium bromide and titanium iodide, into the reactionchamber; d) introducing a reactant gas of at least one of hydrogen,silane, nitrogen and mixtures thereof into the reaction chamber; and e)discharging plasma inside the reaction chamber to deposit the titaniumcontaining film onto the substrate.
 2. The process of claim 1, wherein adeposition pressure between 0.2 and 2 Torr is maintained.
 3. The processof claim 1, wherein the reaction chamber is a hot wall reaction chamber.4. The process of claim 1, wherein the reaction chamber is a cold wallreaction chamber and the given temperature is in the range of 200° C. to350° C.
 5. The process of claim 1, wherein the given temperature is lessthan 400° C.
 6. The process of claim 1, wherein the reactant gascomprises hydrogen.
 7. The process of claim 1, wherein the reactant gascomprises hydrogen and silane.
 8. The process of claim 1, wherein thereactant gas comprises hydrogen and nitrogen.
 9. A chemical vapordeposition process for depositing titanium containing film on asubstrate, the process comprising the steps of: a) disposing thesubstrate inside a cold wall reaction chamber; b) bringing the substrateto a temperature less than 400° C.; c) introducing a titanium source gasinto the reaction chamber, the titanium source gas being one of titaniumbromide and titanium iodide; d) introducing a reactant gas of at leastone of hydrogen, silane, nitrogen and mixtures thereof into the reactionchamber; and e) discharging plasma inside the reaction chamber todeposit the titanium containing film onto the substrate.
 10. The processof claim 9, wherein the substrate is brought to the given temperature byheating a substrate holder which secures the substrate.
 11. The processof claim 10, wherein the substrate holder is heated to the giventemperature by halogen lamps.
 12. The process of claim 9, wherein thegiven temperature is in the range of 200° C. to 350° C.
 13. The processof claim 9, wherein a deposition pressure between 0.2 and 2 Torr ismaintained.
 14. The process of claim 9, wherein the reactant gascomprises hydrogen.
 15. The process of claim 9, wherein the reactant gascomprises hydrogen and silane.
 16. The process of claim 9, wherein thereactant gas comprises hydrogen and nitrogen.
 17. The proceess of claim9, wherein the plasma is discharged inside the reaction chamber for lessthan 200 seconds.
 18. A chemical vapor deposition process for depositingtitanium-containing films on a substrate, the process comprising thesteps of: a) disposing the substrate inside a reaction chambermaintained at a given temperature; b) introducing a titanium source gasinto the reaction chamber; c) introducing a reactant gas into thereaction chamber; and d) discharging plasma inside the reaction chamberand applying a voltage to substrate to bias the substrate to deposit atitanium-containing film onto the substrate.
 19. The process of claim18, wherein a deposition pressure between 0.2 and 2 Torr is maintained.20. The process of claim 18, wherein the reaction chamber is a hot wallreaction chamber.
 21. The process of claim 18, wherein the reactionchamber is a cold wall reaction chamber.
 22. The process of claim 18,wherein the given temperature is less than 600° C.
 23. The process ofclaim 18, wherein the given temperature is less than 400° C.
 24. Theprocess of claim 18, wherein the titanium source gas is a titaniumtetrahalide.
 25. The process of claim 18, wherein the reactant gas ishydrogen, silane, nitrogen, or mixtures thereof.
 26. The process ofclaim 18, wherein the reactant gas comprises hydrogen.
 27. The processof claim 18, wherein the reactant gas comprises hydrogen and silane. 28.The process of claim 18, wherein the reactant gas comprises hydrogen andnitrogen.
 29. The process of claim 18, wherein the surface of the waferis negatively biased.
 30. The process of claim 18, wherein the voltageapplied to the surface of the wafer is an RF voltage.
 31. A chemicalvapor deposition process for depositing a titanium-containing film on asubstrate, the process comprising the steps of: a) disposing thesubstrate inside a cold wall reaction chamber maintained at a giventemperature; b) introducing a titanium source gas into the reactionchamber; c) introducing a reactant gas of at least one of hydrogen,silane, nitrogen, and mixtures thereof into the reaction chamber; and d)discharging plasma inside the reaction chamber and applying a voltage tothe surface of the wafer to bias the surface to deposit thetitanium-containing film onto the substrate.
 32. The process of claim31, wherein the substrate is brought to the given temperature by heatinga substrate holder which secures the substrate.
 33. The process of claim32, wherein the substrate holder is heated to the given temperature byhalogen lamps.
 34. The process of claim 31, wherein the giventemperature is less than 600° C.
 35. The process of claim 31, whereinthe given temperature is less than 400° C.
 36. The process of claim 14,wherein the titanium source gas is a titanium tetrahalide.
 37. Theprocess of claim 31, wherein the reactant gas is hydrogen, silane,nitrogen, or mixtures thereof.
 38. The process of claim 31, wherein thereactant gas comprises hydrogen.
 39. The process of claim 31, whereinthe reactant gas comprises hydrogen and silane.
 40. The process of claim31, wherein the reactant gas comprises hydrogen and nitrogen.
 41. Theprocess of claim 31, wherein the substrate is negatively biased.
 42. Theprocess of claim 31, wherein the voltage applied to the substrate is anRF voltage.
 43. An in-situ plasma cleaning process for cleaning contactopenings, the process comprising the steps of: a) disposing a substratehaving contact openings inside a reaction chamber; b) bringing thesubstrate to a given temperature; c) introducing a cleaning agent of atleast one of hydrogen, argon, or nitrogen trifluoride into the reactionchamber; and d) discharging plasma inside the reaction chamber andapplying a voltage to the substrate to bias the substrate to removematerial from within the contact openings.
 44. The process of claim 43,wherein the reactor pressure is between 0.2 and 2 Torr is maintained.45. The process of claim 43, wherein the reaction chamber is a hot wallreaction chamber.
 46. The process of claim 43, wherein the reactionchamber is a cold wall reaction chamber.
 47. The process of claim 43,wherein the given temperature is less than 600° C.
 48. The process ofclaim 43, wherein the given temperature is less than 400° C.
 49. Theprocess of claim 43, wherein hydrogen is added subsequent to nitrogentrifluoride and argon.
 50. The process of claim 43, wherein the voltageapplied to the substrate is an RF voltage.